1. Field of the Invention
The present invention relates to a pedal driving device of a standing type bicycle, and more particularly to an improved pedal driving device with simple, economic, user-friendly and convenient features and capable of providing a clash-free, smooth, comfortable and safe pedaling operation of a standing type bicycle and satisfying the actual applicability and design requirements.
2. Description of the Prior Art
With reference to FIG. 1 for a conventional standing type bicycle, the standing type bicycle comprises: a frame 10 having a front fork 102 installed to a front tube 101 at the front of the frame, a front wheel 11 installed at the bottom of the front fork 102, and a control rod 12 with a handle 121 installed at the top of the front fork 102 for controlling the traveling direction of the front wheel 11; a rear wheel 13 pivotally installed at the rear of the frame 10; a first rotating shaft 14 and a second rotating shaft 15, respectively and pivotally installed to the frame 10 and between the front and rear wheels 11, 13 with an appropriate distance apart from one another, and a first crank 16 and a second crank 17 being installed in opposite directions to each other and at both ends of the first and second rotating shafts 14, 15 respectively, and other ends of the first and second cranks 16, 17 being respectively and pivotally coupled the front and rear ends of pedal 18 by pivots 161, 171, such that when forces are applied to the pedals 18, the first and second cranks 16, 17 are operated synchronously; a transmission sprocket 19, 20, installed separately at the second rotating shaft 15 and the rear wheel rotating shaft 131; and a transmission chain 21 installed between the two transmission sprockets 19, 20, such that when a user steps on pedals 18 by both legs to rotate the first and second cranks 16, 17 by the first and second rotating shafts 14, 15 respectively, the rotating second rotating shaft 15 together with the coaxial transmission sprocket 19 will drive the transmission sprocket 20 of the rear wheel rotating shaft 131 to rotate through the transmission chain 21, so as to rotate the rear wheel 13 together and drive the front wheel 11 to drive the bicycle to move forward. When use, a rider stands on the left and right pedals 18 and steps on the left and right pedals alternately by both legs. Since an end of the first or second crank 16, 17 is installed to the first or second rotating shaft 14, 15, and another end of the first or second crank 16, 17 is pivotally coupled to the front or rear end of the pedal 18 by a pivot 161, 171, therefore when forces are applied to the pedals 18, the first and second rotating shafts 14, 15 are used as rotation points to loop in an elliptical track by using the first and second cranks 16 respectively as a radius. In the meantime, the rotating second rotating shaft 15 can drive the rear wheel 13 to rotate and drive the bicycle through the transmission sprockets 19, 20 and the transmission chain 21, so as to achieve the effect of riding a standing type bicycle.
Undeniably, the aforementioned method can achieve the effect of riding and driving a standing type bicycle, but its practical application still has the following drawbacks. Since the first and second cranks 16, 17 use the first and second rotating shafts 14, 15 as rotation points to loop in an elliptical track, the stepping forces applied onto the pedals 18 are exerted onto the pivots 161, 171 at both front and rear ends respectively. However, when the rider stands on the bicycle and steps on the pedals 18 alternately by both legs, the forces cannot be exerted onto the two pivots 161, 171 at the front and rear ends uniformly, but the forces will be applied at corresponding positions of the pedals 18 in different angles while the pedals 18 are rotating in an elliptical track. As a result, when the pedals 18 and the first and second cranks 16, 17 are rotated to a horizontal position and aligned linearly with each other, the non-uniform stepping forces applied to the front and rear pivots 161, 171 will cause the first and second cranks 16, 17 to produce clashes and unsmooth rotations. Particularly, when the left and right pedals 18 are idle and aligned horizontally and linearly, any further applying force will cause clashes or even jams of the first and second cranks 16, 17. Obviously, such unsmooth, uncomfortable and unsafe ride requires improvements.
In view of the aforementioned shortcomings of the prior art, the inventor of the present invention based on years of experience in the bicycle industry to conduct extensive researches and experiments, and finally developed the improved pedal driving device of a standing type bicycle to overcome the shortcomings of the prior art.